Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!wuarchive!cs.utexas.edu!texbell!sugar!karl From: karl@sugar.hackercorp.com (Karl Lehenbauer) Newsgroups: comp.sys.amiga Subject: Re: Commodore, Amiga, Apple, and MAC Message-ID: <5542@sugar.hackercorp.com> Date: 8 Apr 90 15:06:35 GMT References: <23800@pasteur.Berkeley.EDU> Reply-To: karl@sugar.hackercorp.com (Karl Lehenbauer) Organization: Sugar Land Unix - Houston Lines: 36 In article mwm@raven.pa.dec.com (Mike (Real Amigas have keyboard garages) Meyer) writes: >Much as some Amiga users may hate to admit it, the difference between >preemptive and non-preemptive multitasking isn't that great from the >users point of view. Perhaps. Nonetheless, as an example, the Hackercorp Cybernetic Sequencer (approaching beta test within a few weeks) consists of separate cooperating tasks for MIDI playback, MIDI recording, standard MIDI file loading, standard MIDI file saving, the MIDI clock, the SMPTE clock, Amiga sample playing as a MIDI synth, and the user interface. Although the loader and saver could be nonpreemptive, and the clock programs really just set up interrupt handlers, the MIDI recorder, MIDI player and sample player could not be tasks under a non-preemptive or non-realtime exec -- their functionality would have to be encoded into an interrupt handler. Granted, these mainly affect the developer, as you said, but they do buy the user some things. What? Well, the ability to play a song while simultaneously loading other ones, not requiring the saver or recorder to be present in a playback-only (i.e. performance) environment (could be handled with overlays, but ick), the ability to use the recorder and player simultaneously in kinky ways, the eventual ability to (hopefully) do simultaneous animations, IFF picture displaying, fading, wiping, etc, i.e. multimedia and, as long as the priorities are set up correctly, the ability to run other programs simultaneously with these programs without their affecting the hard-realtime time-critical aspects of those activities. And the preemptive multitasking may not be apparent to the user, but I would argue that its presence on the Amiga (in conjunction of course with the blitter) substantially contributes to the Amiga's higher windowing performance than, say, the Mac, for a given CPU type and clock speed. In other words, having to constantly explicitly pass control to other tasks can substantially decrease performance, which does ultimately affect the user. -- -- uunet!sugar!karl "I hate quotations. Tell me what you know." -- Emerson -- Usenet access: (713) 438-5018